The present invention relates generally to hydropneumatic devices and more particularly to a pressure reservoir or accumulator which is particularly adapted for use with the shock absorber of a vehicle. The invention is particularly concerned with the type of pressure reservoir wherein a housing has a diaphragm located therein to separate the housing into a gas chamber and a liquid chamber, which liquid chamber is in communication with a shock absorber. The diaphragm is normally pressed against the inner wall of the housing by compressed gas on a side of the diaphragm opposite the liquid chamber and the liquid enters and leaves the liquid chamber through an opening in the housing wall.
In the utilization of hydropneumatic pressure reservoirs of the type described, particularly in connection with shock absorbers which are mounted in a vehicle, there will normally arise the requirement that the outer diameter of the apparatus be as small as possible for a given nominal volume. In known devices, the general construction has usually involved a spherical configuration and pressure reservoirs of the prior art are normally equipped with diaphragms which are adjusted to this spherical shape. Pressure reservoirs of this type may have a relatively large outer diameter and they therefore may not be suitable for use in connection with shock absorbers used in certain applications, particularly those used in connection with motorcycles.
In order to take into account the conditions of a given installation and the required shape of the pressure reservoirs, another known embodiment in the prior art involves a reservoir which is constructed as a cylindrical container wherein the axial structural length is large with relation to the diameter. As a result, it is not possible to achieve an ideal ratio of length to diameter which should be about 1:1 for the reservoir in respect to the design of the diaphragm. Furthermore, in order to enable realization of a large nominal volume, it is necessary to maintain the distances between the diaphragm and the inner wall of the reservoir relatively small. The shape of known reservoirs has the disadvantage that between the diaphragm and the inner wall of the housing or liquid container, bubbles may be formed when the liquid is to be emitted from the reservoir. As a rule, repeated introduction and emission of the liquid from the liquid container is involved and thus the liquid cannot flow off into the working chamber of the shock absorber as a result of the bubbles which may be accumulated. This may lead to a liquid deficit in the adjacent working chamber so that the diaphragm may expand more than is desirable in the direction of the outlet opening leading from the liquid chamber to a working chamber of the shock absorber. This expansion may occur to such an extend that the diaphragm may be forced into the inlet/outlet opening of the liquid chamber and may therefore become damaged as a result.
The present invention is directed toward avoiding disadvantages of known constructions and toward provision of a hydropneumatic pressure reservoir which will facilitate functioning of the apparatus in all states of operation. The invention aims toward provision of a structure wherein the load on the diaphragm is lowered and wherein there is prevented formation of liquid pockets between the reservoir housing and the diaphragm.